AVS 49th International Symposium
    Organic Films and Devices Wednesday Sessions
       Session OF+EL-WeP

Paper OF+EL-WeP10
The Surface Stress under Ion Irradiation on Si and SAM-coated Si

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Organic Films and Devices
Presenter: A.N. Itakura, Institute for Materials Science, Japan
Authors: A.N. Itakura, Institute for Materials Science, Japan
M. Kitajima, Institute for Materials Science, Japan
R. Berger, IBM Deutschland Speichersysteme GmbH, Germany
Correspondent: Click to Email
Evaluation of stress in the Si stencil mask is very important for ion projection patterning or ion lithography technology, because the stresses would cause a deformation of the projected patterns. Ar ion irradiation makes a compressive stress on Si(001) surfaces.@footnote 1@ Stencil masks often become folded during the ion projection patternings, which should be owing to this ion induced compressive stress. In this paper, we have studied the stress evolution of Si membranes under ion irradiation. Bare Si and alkanethiol-coated-Si were examined during ion irradiation from ion energies of 5 to 50eV. The stresses were in-situ real-time monitored by using a microcantilever sensor technique combined with ion irradiation system in UHV. Self-assembled monolayers (SAM) such as alkanethiol, HS-(CH@sub2@)@sub n-1@-CH@sub 3@ for n=4,6,8,12, on gold induced compressive stresses.@footnote 2@ In contrast to the compressive stress during SAM growth, a strong tensile surface stress of about -0.7 N/m was found when the sensor is exposed to Ar ions. This value is 3-4 times larger than the compressive stress. The constant value of the tensile stress for an Ar-ion dose higher than 4 x 10@super 14@ ions/cm@super 2@ indicates that a stable monolayer forms during Ar-ion irradiation. Stable protective monolayers featuring tensile stress can play a key role in micro-machining and as protective overlayers for silicon mask lithography. @FootnoteText@ @footnote 1@T.Narushima, A.N.Itakura and M.Kitajima, Appl.Phys.Lett.79, 605-607 (2001), @footnote 2@A.N.Itakura, R.Berger, T.Narushima and M.Kitajima, Appl.Phys.Lett.(2002), in printing.